This invention relates to a machine for metering and grinding friable material.
Known machines for grinding various materials include, for example, hammer mills which comprise a rotor consisting of a rotary shaft to which are connected radial arms that beat the material to be ground against a cylindrical screen at least partly surrounding the rotor.
Another known mill comprises a rotor consisting of a rotary shaft with a flange at either end, bars parallel to the shaft being fixed to the periphery of the flanges and the rotor turning either always in the same direction or alternately in one direction and then the other within a cylindrical screen.
These known grinding machines or mills are generally of sophisticated construction. Obtaining regular grinding or granulation with these known machines requires a regular dosage to ensure a constant charge and a constant level in the mill.
Known feed units which may be used to feed these known mills include, for example, screw feeders, particularly of the type comprising an Archimedean screw or a helical screw. A screw feeder of this type may be accommodated in a cylindrical casing or tube open at its downstream end, a feed hopper being provided at the upstream end of the tube.